The headline is weird - instead of legalising, it should say "decriminalises" in my opinion. Someone made it illegal at some point. The headline now seems to indicate "we've made a new law that allows it", but that makes it like it's an exception.
Importantly, like the US, UK and Australia, India is a "Common Law" nation. That means court rulings set binding legal precedents which can only be overruled by higher courts or actual legislation introduced later. In short: A judgement becomes law.
This is opposed to "Civil Law" societies (most of the rest) where court rulings do not set legal precedent, and might only be "persuasive" to other judges in other cases. Plenty of exceptions depending on the country, which court, etc. but that's a general overview.
Perhaps for people from Civil Law countries it would be odd to hear that a court has legalised something.
You can "decriminalise" something either by eliminating the entire piece of legislation, or by amending it to remove the criminal act within it. In the case of the latter, that leaves open the option of replacing it with other words that might indicate civil penalties. If that happens, that is still decriminalisation, and would be distinct from legalisation.