Shortcut to switch language on Macbook Air

I am using US and VN languages. I often switch the two languages back and forth. I have to drag mouse to the language icon and click to switch it. I am tired of doing a lot of steps. I have already searched on google looking for a shortcut to help me faster switching between US and VN. But, the instruction is not similar with my mac.

I don't know how to do next with it.