'Understands' in the Bible

But as for the seed sown on good soil, this is the person who hears the word and understands. He bears fruit, yielding a hundred, sixty, or thirty times what was sown."

there is no one who understands, there is no one who seeks God.

For the one speaking in a tongue does not speak to people but to God, for no one understands; he is speaking mysteries by the Spirit.

he is conceited and understands nothing, but has an unhealthy interest in controversies and verbal disputes. This gives rise to envy, dissension, slanders, evil suspicions,