Hola Allison

We sometimes use the present tense to refer to future events, always using a time phrase that indicates the future. This is the case with this sentence:

"Esta tarde ayudo a mi madre en el jardín."

If you only say "Ayudo a mi madre en el jardín." there is no indication of future, but with "esta tarde" we know it is referring to a future time, "this afternoon".

I hope this helps.

(We've got a lesson about this usage coming up soon.)

Inma