pen
The French word for pen is "stylo". It is used in the same way as in English to refer to a writing instrument. It can also be used to refer to a pen for drawing or sketching.
He uses a pen to write a letter.
This sentence talks about a person who is using a pen to write a letter. Here, 'un stylo' is used as the means to perform the action of writing.
I lost my pen.
In this sentence, the speaker lost their pen. 'Mon stylo' refers to the speaker's pen.
Can you lend me a pen?
This is a question where the speaker is asking someone else to lend them a pen. 'Un stylo' is the object that the speaker is asking to borrow.