Sunblock is a cream or lotion that you put on your skin to keep the sun from burning it.
Sunblock is good for your skin and helps keep you safe from the sun.
Examples:
I put sunblock on my arms before going to the beach.
Mom always makes me wear sunblock at the pool.
Sunblock smells like coconuts.
I don't want to wear sunblock, but I have to!
I need to wear sunblock or I'll turn into a lobster!
The sunblock is in the bag, next to the towel.