Jesus teachings stands apart from others for many reasons. Among the reasons, the most important one is the parables, illustrations and examples used by master can be understood by any person of any level of intelligence irrespective of the time. As you start learning more and more, you understand HIM deeper and deeper. Applicability and relevance of his illustrations stands true at all times to various levels of intellectuals is the biggest quality of his teachings.
In this case, though there is many explanations including the one of fig fruits representing Israel and the what is going to happen to Israel, I would like to think in a very simple way, because Jesus has told this illustration to very simple unqualified[in our eyes] fishermen people - his disciples- to understand.
My understanding is as follows:
This has happened just the day before the cleansing of the Jerusalem temple. That day he went to the temple in the evening and looked at everything inside very carefully and went out. He must have been very disturbed .....