Button function not working

why his code is not working

The " f " in function declaration must be small , but in your code " Function say_hello( ) " it is capital.

JavaScript is case sensitive
so in your code for function you have used F make sure that it is in lowercase…

Check this code instead of your code :
write this code in between script tags
function say_hello() {
setTimeout(alert(“Hello”), 3000);

for me as well, the button function is not working. I have tried all the possible ways. Please help me with the same.