Whenever your Zap successfully automates something, it's called a task. Trigger steps do not count as tasks, but successful action steps do. A single Zap can automate one or more tasks, depending on how many action steps it has. You can see all the tasks your Zaps have attempted in Task History.
If you have a Zap set up to send you a text message every time someone completes a transaction in your online store, that text message counts as a task. If you want to send a text message and also add a row to a spreadsheet, the text message and the spreadsheet row both count as tasks.