If something is sketchy, it is not clear or not complete. It might make you feel unsure or worried.
The word sketchy can make people feel uneasy or suspicious.
Examples:
The directions to his house were sketchy.
I don't trust that guy, he seems sketchy.
The plan seems a little sketchy to me.
I heard a sketchy noise in the dark!
The bridge looks sketchy, I don't want to cross it.
The old house looks really sketchy, like a haunted house.