Hello Eli
I think you are talking about “gerunds”, which are verbs which can be used as nouns.
Example “he likes swimming”
He = subject
Likes = verb
Swimming = object (noun)
The main verb is “like”. “Swimming” is the name of the activity, but does not act like the main verb.
You can find more on google if you search for “gerunds”. There are many rules but I hope this helps.