Can anyone explain sentences like “it’s two things” “video games are a great source of learning”

These are sentences I’ve seen that don’t seem to follow the singular-plural rules Are they grammatically correct? If they are how do they work exactly? Thank you in advance!

Solution 1:

In "It's two things", "it" is a single object. The two things are different ways to categorize that one object. The verb agrees with the subject.

It's two things: a floor wax and a desert topping.

If you actually had multiple objects, the pronoun would be "they", not "it", and you would use a plural verb.

In the video game example, "great source of learning" refers to the entire collection of games, not individual games, so it's singular. But we still use a plural verb because "video games" is plural.

Actually, I think both "a great source" and "great sources" would be acceptable, since you can treat them as a collective or as individual games.