Water Leak and Part ID

[Bacon_ISF]

Hello TFP - I have a bad leak in the part circled below. Would anyone be able to ID what it is? and what needs to be done to stop the leak?
It looks like some sort of an air release and water is overflowing through it.
Thanks

https://imgur.com/a/oz9HZMf

 

[kadavis]

That is a vacuum breaker to keep the spa from draining back to the pool when pump is off. Depending on the size thread usually 1/2" you could get something like this,0556030 - Watts 0556030 - 1/2" LFN36M1 Lead Free Water Service Vacuum Relief Valve. Or you could cut it out and replace with a Jandy type check valve