A saltire is a cross that is shaped like a diagonal 'X'.
A saltire is often seen on flags and coats of arms.
Examples:
The flag has a red saltire on it.
The coat of arms has a blue saltire.
The yellow saltire is on the flag.
The saltire is like two lines that make an 'X'.
The big castle has a saltire on its flag.
The knight's shield has a silver saltire on it.