Unity Alert or Trace

Is there a way to trace out some text, or fire a pop up alert in unity to make sure you are getting into a specified function or get the value of specific variables?

Yes, Debug.Log() will output text or the contents of an object to the console tab.

Michael's answer is correct, but for showing variable values, there is another option that I recently found. You can put the Inspector into Debug mode (via the drop-down triangle on the right side), which lets you see all variables in a script, not just the public ones.

They do have to be permanent variables, declared outside of a function (if you declared a temporary var in Start(), for instance, it would be gone). But they don't have to be declared public, to be visible in Debug mode.