‘It’s’ is a contraction for ‘it is.’ By stating ‘it’s no use’ you are saying that what you or someone else is doing is not recommended or uncalled for.
Here are some examples:
“It’s no use crying.”
“It’s no use separating them.”
“It’s no use talking to her.”
“It’s no use whining about it.”
“It’s no use apologizing.”
“It’s no use attempting to please him.”
“It’s no use arguing about it.”
“It’s no use behaving that way.”
“It’s no use cleaning up.”
“It’s no use checking on it yet.“