In French there really are three ways to express varying degrees of "futureness", not unlike English:

(1) Je vais au restaurant plus tard. -- I'm going to the restaurant later. (a bit colloquial)(2) Je vais aller au restaurant plus tard. -- I'm going to go to the restaurant later. (3) J'irai au restaurant plus tard. -- I will go to the restaurant later.

To express the least temporal distance into the future you simply use present tense. In English one often uses present continuous. A bit farther into the future, you often employ the future proche, very much like the English "going to". And finally, the future simple for events with the largest separation from the present.

"Je vais"     is present tense, not any aspect of future.

If you want to express a future action you would need to write "Je vais aller......"

"I am going to go"  -----  near future    or  "Je irai ...."   "I wiil (shall) go...."  future.

The text in your query  simply states "I go to the restaurant later" "je vais au restaurant plus tard"

Je vais is present tense alright. But the present tense is frequently used to express aspects of the near future in French.