How do I know whether this is a function or not? And can someone EXPLAIN the steps on how to determine on how it would be a function please?

Answer:
Yes
Step-by-step explanation:
A function would be f(x), a output for each x input.
The slope intercept form is y - mx + b! *keep this in mind*
If you graph this as well, it would be easier to see if its a function too. If the line crosses through it once, it is indeed a function. If it doesn't, it isn't
Hope this helps