Meaning of "by some margin"

Could you please explain the meaning of this? I have it in a sentence - The speaker was, by some margin, the youngest person in the room. I am a translator from English to Czech and I can´t find it anywhere. Thanks.

It means by some non-zero or at least non-negligible margin (difference, or delta). IOW, it means that the person was considerably younger than everyone else.

Margin:

an additional amount or one beyond the minimum necessary.

If the speaker was younger than the others by one year, that would not be a big deal - someone has to be the youngest.

But if he was the youngest by a number of years, that is a significant margin.

By some margin, you are saying, by a number of years.