"Learnings" is the plural of "learning" in the sense of "(specific) things or lessons that have been learned". It is often considered nonstandard English, even though it is rather widely used. If you are only talking about general knowledge rather than specific things you have learned, I would definitely use the singular "learning".
Wiktionary has rather thorough usage comments on the word "learnings": https://en.wiktionary.org/wiki/learnings
The term learnings was not in common use in the 19th and 20th century, though the countable noun sense learning (“thing learned”) dates to Middle English (14th century; see leornyng), and the plural learnings to Early Modern English. Note that early use of learnings often have the sense or connotation “teachings” (see examples above), as was the case of learn generally. It has found occasional use for centuries, including by Shakespeare, and parallel constructions are commonplace – compare teachings and findings.
However, from circa 2000 it became a buzzword in business speak, particularly in constructions such as “key learnings” or “apply these learnings”; this was preceded by occasional educational use from the 1950s. Some disapprove of this, and it sounds ungrammatical enough to be used as an example of broken English, as in the comedy Borat: Cultural Learnings of America for Make Benefit Glorious Nation of Kazakhstan (2006). Suggested alternatives include lessons learned, “things one learned” – or simply lessons – discoveries, findings, insights, and takeaways.
"Learning to live with ‘learnings’" from CS Monitor (2021) comments:
Learnings is often seen as pretentious and useless business jargon, but its cousin teachings is pretty unobjectionable. What’s the difference?
Learnings surged in popularity during the 1950s, in business jargon and edu-speak, which did little to make it seem more “correct.” But it is now used widely. We’ll have to endure learnings for the foreseeable future.