Mostly information about making drugs that are frequently abused, but it's hard to say specifically what qualifies since some law bans just "propaganda" and what is "propaganda" is for any local judge to decide, and decide they do. And some bans information such as "growing plants containing narcotic drugs" - so if you are a gardener and want to know how to grow a poppy flower, woe is to you. Also if you are chemist and want to make an experiment involving acetone (it's a "drug precursor"). And so on.

Some more general information in English here: https://en.wikipedia.org/wiki/Russian_Internet_Restriction_B... but this is not the only law, there are many additional bans (Russian parliament is sometimes called "crazy printer" in Russia because it has issued so many insane laws). You can read about banning Wikipedia here: https://en.wikipedia.org/wiki/Blocking_Wikipedia_in_Russia

It is implied that the parent comment was talking about illegal drugs.

Interesting side fact: unlike in english, there are two completely distinct words for illegal and legal drugs in russian language. Which a lot of times makes it easier to spot russian-speaking posters, as they tend to refer to illegal drugs as just "drugs", while referring to legal ones using other more specific terms, like "pills" or something else.