What is considered a submission?

I see that the free plan has a limit of 100 submissions. what is a submission exactly?  I have had 103 submissions, in the sense that clients have filled out the form and sent it to me.  but when I check my account I notice that I have listed 0 out of 100 submissions. so I am confused.

This 100 submissions (on free accounts) limit are per month. The submission counter gets reset once at the beginning of each month.

Every time someone fills in one of your forms and hits submit is counted as one submission. But again, the submissions counter get reset once per month, so in order to know how many submissions you've had this month you can select the human shaped icon in the top-right of your screen:

Let us know if we can assist you further.