Start a sentence with verb.

(you) / close / door

mean?

What is implied here is the subject is the singular 'you', as opposed to a plural 'they'. So the proper verb complement would be give (not gives) and close (not closes) due to there being a singular subject.

In the context, "Give me the hammer" is correct, because it is addressing dirrectly 2nd person.
Similarly "Please close the window" is correct.
When you describing an event in reference to 3rd person, it's correct to say: "he 'gives me the hammer' and...".
However it's totally incorrect: "Please closes the window" because of two words collide with each other: 'please' - addressing 2nd person, and 'closes' - refers to 3rd person. The word "closes" you can only use in something similar to: "as he 'closes the window' she walks to the room and..."

I hope this helpful.

Thank you.