Hello!
A function will be increasing if the y values are increasing (since this is a function, this will pass the vertical line test, meaning that it is increasing if the y values are increasing).
On interval 1, the function is not increasing since the y value stays constant.
On interval 2, the function is increasing because the y values are increasing.
On interval 3, the function decreases because the y values are decreasing.
On interval 4, the function increases again.
On interval 5, the function stays the same because of its constant y value.
To reiterate, on intervals 2 and 4, the function is increasing.
Hope this helps!