Yes it’s a function
It’s a function because each input (the x) only has 1 output (the y)
An example where it wouldn’t be a function is a table like this:
1 | 4
1 | 5
2 | 7
3 | 12
4 | 19
Because 1 maps both to 4 and 5 so it’s not a function. But in your original table, it’s fine so it’s a function.