Hi Abednego,
Mat 13:10 And the disciples came and said to Him, "Why do You speak to them in parables?"
v. 11 He answered and said to them, "Because it has been given to you to know the mysteries of the kingdom of heaven, but to them it has not been given.
v. 12 For whoever has, to him more will be given, and he will have abundance; but whoever does not have, even what he has will be taken away from him.
v. 13 Therefore I speak to them in parables, because seeing they do not see, and hearing they do not hear, nor do they understand.
Concerning verse 12, it appears to me to just be repeating what Christ had already stated in verse 11. So look first at v. 12 "For whoever has," has what? Well look at verse 11, has "the mysteries of the kingdom," or this TRUTH. Back to verse 12 "to him more will be given, and he will have abundance;" a couple of Scriptures can help with this part.
Php 1:6 being confident of this very thing, that He who has begun a good work in you will complete it until the day of Jesus Christ;
2Co 9:8 And God is able to make all grace abound toward you, that you, always having all sufficiency in all things, may have an abundance for every good work.
Here is the last part of verse 12, "but whoever does not have, even what he has will be taken away from him." On the day of judgment everyone will give account and if your understanding is not truth, but the herical teaching of the church, it will be burned out and "taken away." Here are a couple more verses to help with this part.
1Co 3:13 each one's work will become clear; for the Day will declare it, because it will be revealed by fire; and the fire will test each one's work, of what sort it is.
1Co 3:15 If anyone's work is burned, he will suffer loss; but he himself will be saved, yet so as through fire.
Hope that is helpful.
mercy, peace and love
Kat