Maybe you're thinking about the present continuous tense which describes an activity at the time of speaking ?
"I am going to the beach" is present continuous and describes what you are doing now, or the immediate future.
Notice how this differs from, "I will go the beach". This describe a future action, not a present/immediate future action.
When to use 'will' and when to use 'going to' is actually quite complex, and you need pages of examples. Some circumstances they are completely interchangeable, other times one or the other is required, and in other instances each will have a different nuance.