Luke 13:6-9 (KJV)
6 He spake also this parable; A certain man had a fig tree planted in his vineyard; and he came and sought fruit thereon, and found none.
7 Then said he unto the dresser of his vineyard, Behold, these three years I come seeking fruit on this fig tree, and find none: cut it down; why cumbereth it the ground?
8 And he answering said unto him, Lord, let it alone this year also, till I shall dig about it, and dung it:
9 And if it bear fruit, well: and if not, then after that thou shalt cut it down.
Israel can be depicted as a fig tree. The message that John the Baptist preached was “Luke 3:7-8 (KJV) Then said he to the multitude that came forth to be baptized of him, O generation of vipers, who hath warned you to flee from the wrath to come? 8 Bring forth therefore fruits worthy of repentance, and begin not to say within yourselves, We have Abraham to our father: for I say unto you, That God is able of these stones to raise up children unto Abraham.” Jesus Christ wanted GOD’s people to repent and bear fruits worthy of repentance. We can see that some time after Jesus Christ death and resurrection judgment came and the temple was destroyed, etc.. Now since the recreation of the state of Israel GOD is on the way of fulfilling more of His promises to them.

We also can apply this parable to everyone. 
Bible Knowledge commentary states: “This parable illustrates the point made in Luk 13:1-5 that judgment comes on those who do not repent. Here Jesus took the thought one step further and noted that fruit must be present (cf. Mat 3:7-10; Mat 7:15-21; Luk 8:15). A visible change must be seen in the life of one who claims to trust the Messiah. If there is no visible change that person, like the figless fig tree, is judged. ”
GOD is so patient with people that He gives time to repent when people have not repented. But there will come a time when GOD will judge and punish, those who have not repented. Repentance results in change of behaviour. One can not say I am sorry for my sin and but deep down one is not sorry and then keep doing it. There are changes that are immediate and others are progressive (depending on how the LORD is working in us). Like the fig tree it requires time to bear fruit but fruit will be born if there is true repentance. The digging and fertilising can be compared with the work of the Holy Spirit and the Word of God in the persons life.

Let us pray for open and soft hearts that when the seed of the Word of God comes that it will bear fruit “Matthew 13:23 (KJV) But he that received seed into the good ground is he that heareth the word, and understandeth it; which also beareth fruit, and bringeth forth, some an hundredfold, some sixty, some thirty.” (see Matthew 13:1-9,18-23) 

For more on repentance have a look at https://missioncommunities.network/category/scripture/repentance/