This is a subject that I'm obviously quite passionate about. I've researched it quite extensively. I quickly discovered to this day it remains somewhat shrouded in mystery. For one, there is still a lack of good basic science on the topic and plenty of magazine and online articles that promote false, incomplete or outdated information. Some scientists still think that squirting is in fact coital incontinence! It's crazy to think that we probably know more about the moon that we know about the vagina and how it works!
There is no consensus and rather confusion between the terms squirting and ejaculation which are often used interchangeably. From what I gathered, squirting (the sometimes forceful clear liquid) comes from the bladder through the urethra. Its composition varies and it may include pee. There are claims that the clear squirting liquid is produced by the Skene's gland (aka the female prostate) a small "pouch" under the bladder and on the ceiling of the vagina, which is what is stimulated when pressing the G-spot. It has 2 conduits which are located on both side of urethra above the vagina (more on that below) and it also drains into the bladder (which would be where that clear squirting liquid comes from).
Then there is the white creamy substance that can be secreted during intercourse. It would make sense to call that female ejaculation since it looks like sperm and apparently its composition has similarity. (it contains prostatic acid phosphatase (PSA). PSA is an enzyme present in male semen as well as fructose! ) Now that creamy stuff is also said to be produced by the Skene's Gland but delivered by those 2 conduits at the front of the vagina below the urethra. Because of its composition similar to sperm, one theory is that it would help with sperm motility. (not a typo that is a word look it up). A natural female mechanism that would help fertilization and reproduction.
The actual purpose of squirting is unclear. Some scientists believe it would function to prevent UTI (urinary tract infection) again based on analysis of that liquid. Its location would make it strategically well positioned for that. Another theory I've heard is when a woman gives birth, the baby's head typically rubs against the g-spot and may provoke squirting and that sense of "pushing". That liquid could help facilitate the delivery of the baby or perhaps its anti-bacterial properties would help protect the baby from infection? When you think about it, it's not that long ago that women would give birth in the bush and far from ideal sanitary conditions.
And one more thing to make this all even more mysterious, apparently 1/3 of females do not have the Skene's gland! Which could explain not all female can squirt. That could also suggest just like molars and other organs that we have but don't absolutely need to survive ( gallbladder, the spleen, tonsils etc.) that we are a work-in-progress and evolving and as our habits, environment, habitat changes so does the human body. What is no longer needed for our survival eventually will disappear. (sorry creationists out there)
Back on topic, there is also the Bartholin's glands with 2 lower openings on both side of the vagina that also secret mucus for lubrication. There isn't a ton of info on that either but I imagine they would be responsible for the regular vaginal wetness.
I'm not a gynecologist or scientist so I can only rely on the information I gathered and my personal experience and the discussions I have had. I'm not attached to my views as it's not my life's work / personal research so I will change my position the moment I find compelling information and evidence to support it.
One thing is sure not all women can squirt just like not all women are fertile. So I would advise not to put too much hope for this. Better not to have any expectations and enjoy the surprise if it does happen. The success of the session is solely based on your comfort and pleasure.
Some good articles I found.
https://www.netdoctor.co.uk/healthy-living/sex-life/a2295/female-ejaculation/ https://www.health.com/sexual-health/female-ejaculation https://www.medicalnewstoday.com/articles/323953.php https://www.healthline.com/health/healthy-sex/female-ejaculation#if-it-doesn't-happen