Really interesting question!
It seems like the meaning of practical here is a combination of several of the definitions you linked, though I see why none of them seem to fit exactly. If I were to replace the word practical in that sentence, I would say something like:
A small piece of useful/helpful/situationally-relevant information or advice.
So that's what it means, but none of the definitions you linked seem to fit perfectly. I went looking and found this other definition on The Free Dictionary, and it seems closer to what you're talking about here:
4. Capable of or suitable to being used or put into effect; useful: practical knowledge of Japanese. See Usage Note at practicable.
And as that usage note is actually quite interesting and useful, I'll include the text here as well:
Usage Note: It is easy to confuse practicable and practical because they look so much alike and overlap in meaning. Practicable means "feasible" as well as "usable," and it cannot be applied to persons. Practical has at least eight meanings, including the sense "capable of being put into effect, useful," wherein the confusion with practicable arises. But there is a subtle distinction between these words that is worth keeping. For the purpose of ordering coffee in a Parisian café, if would be practical (that is, useful) to learn some French, but it still might not be practicable for someone with a busy schedule and little time to learn.