“He has a weird sense of humor.”

Your uncle laughs at strange things and makes jokes without laughing. You don't understand him. Now you're talking with your mother about him. You say:

He has a weird sense of humor.

a weird (something)

"Weird" means "strange". "Strange" has a wider meaning than "weird". You can call things that are not normal "strange" or "weird". But you can also use "strange" for something that you don't know about, even if it's normal:

There was a strange man on my back porch, so I called the cops.

This means that you didn't know the man. Even if he looked like a normal person, he would still be "a strange man" because you didn't know him and he wasn't supposed to be there. Another example:

If you see a strange package, inform the building staff or the police immediately.

have a sense of humor

Someone's "sense of humor" is their style of joking, and also the way that they react to other people's jokes. You can say that someone:

• has a great sense of humor (They don't mind people joking, and maybe they do funny things themselves.)
• doesn't have a sense of humor (They don't laugh at people's jokes. They're too serious.)
• has a witty sense of humor (They come up with intelligent jokes quickly.)
• has a sick sense of humor (They think that disgusting or harmful things are funny.)