To put (something) in a position to obstruct an entrance, opening, etc.; shut.
E.g. "The store is closed at 5pm."
There are different ASL signs for the English word "close" as in "please close the door (or window) for me." "Close the book" and so on, usually using classifier verb phrases.
To close the door.
First 100 words.
As you feel more comfortable with the first few hundreds of ASL signs, progress further with your vocabulary and learn signing more.