'Understand' in the Bible

But these persons, like irrational animals born [only with] natural [instincts] for capture and killing, blaspheming {about things} they do not understand, in their destruction will also be destroyed,

as [he does] also in all his letters, speaking in them about these [things], in which there are some [things] hard to understand, which the ignorant and unstable distort to their own destruction, as [they] also [do] the rest of the scriptures.