“Because at some time in the future”
The context indicates that these will be people who are a part of the community of believers.
“will no longer want to listen to sound teaching”
This means the teaching that is true and correct, according to God’s word.
Paul speaks of people obtaining many teachers as if it were putting them into a heap or pile. AT: “they will listen to many teachers who assure them that there is nothing wrong with their sinful desires” (See: rc://en/ta/man/translate/figs-metaphor)
Paul speaks of people strongly wanting to hear something as if their ears itched and could only be satisfied if teachers taught them what they wanted to hear. AT: “who say only what they want so much to hear” (See: rc://en/ta/man/translate/figs-idiom)
Paul speaks about people no longer paying attention as if they were physically turning away so they cannot hear. AT: “They will no longer pay attention to the truth” (See: rc://en/ta/man/translate/figs-metaphor)
“Turn aside” here is an idiom for “change direction toward.” AT: “they will change direction toward teachings that are not true” (See: rc://en/ta/man/translate/figs-idiom).
Paul wants his readers to think correctly about everything, and he speaks about them as if he wanted them to be sober, that is, not drunk with wine. AT: “think clearly” (See: rc://en/ta/man/translate/figs-metaphor)
This means to tell people about who Jesus is, what he did for them, and how they are to live for him.