What does "<<" mean?

Answer 1

Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand.

Answer 2

Operator for standard user output

Answer 3

Stream insertion operator... perhaps ;)

Answer 4

" << " is like the top of an arrow. If it' s like this " << " ,it means that the arrow is going out so that is cout or output. In the other case ( >> ) it means that the top of the arrow is going in : in fact, in this case the arrow rapresent cin or input.
Do you understand ?

Answer 5

cout<<......