Learn English – “Bury” — noun meaning

Here are the three meanings of pro:

• (noun) professional. Example: Don't mess with me. I'm a pro!

• (noun) advantage. Used mainly within the context of pros and cons (advantages and disadvantages). Example: The pros of democratic governance far outweigh the cons.

• (preposition/adverb) in support of. Example: I'm a pro-choice activist.

In your example, pro-American is an adjective (pro functions as a preposition here), and as such, it should always be hyphenated. Example: His views are definitely pro-American. On the other hand, pro America is an adverbial phrase and it should not be hyphenated. Example: The Non-Aligned Movement has never been pro America.

That is ill-informed nonsense. Of course it’s a noun. Point the tweeter in the direction of Alexander Pope’s couplet, both for the usage and the sentiment:

A little learning is a dangerous thing;

Drink deep, or taste not the Pierian spring.

It is not entirely clear whether the tweeter had the plural form particularly in mind, but, if so, its use is not unprecedented. In Cymbeline, I. i. 43 the First Gentleman says:

The king . . . Puts to him all the Learnings that his time Could make him the receiuer of.

Francis Bacon uses it at least twice:

Particular and positive learnings of lawes doe easily decline from a good temper of iustice.

and

He did send his diuine truth into the world, wayted on with other Learnings.