How is this a function

y = 'the square root' of' (X + 2)

if you plug in the value 2 for X,
y will equal either -2 or 2.
I thought functions have only one y value for every x value.

as far as I can tell you are correct and this isn't a function

No, this is a function. The input x=2 leads to the output y=2. To get an output of -2, the relation has to be defined as y=-sqrt(x+2)... that is, you need a minus sign in front.

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Brian is right. y=√(x+2) is a function because in this case, only the positive root is considered.

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y = sqrt(x+2) is not a function unless you specify whether you take the positive or negative root.