"Context" is extra information that helps you to understand something better. For example, if you're listening to someone speaking in a foreign language, their facial expressions and hand gestures give you some context for what they're saying.
"Putting ___ in context" means making a topic easier to understand by giving extra information about the time, place, situation, history, and so on.
So you can use this expression to introduce contextual information about something:
To put it in context, at that time the most powerful personal computers were only able to do simple math equations.
To put his speech in cultural context, politicians in India rarely retire. So him announcing that he was leaving the party was rather shocking.
This expression sounds very intellectual. Use it when you're giving a speech or lecture.