A conversation is talk between two or more people, usually informal, where they share thoughts, questions, or news.
Hi, how was your weekend? Busy, but good, thanks! That short exchange is a conversation.
Examples you might hear
A conversation can be about anything. Two people might talk after a match: We had a conversation about football. I thought the goalkeeper played badly. Really? I thought he was great. That is two people swapping opinions on a match, with one disagreeing with the other. You can count them too: a brief conversation just means a short one. That is the word in action.
A telephone conversation: the word also covers talk by phone, not only face to face. I had a long conversation with my aunt on the phone last night. Same back-and-forth talk, just over a call.
Conversation and a speech are not the same thing
A word people sometimes mix up with conversation is speech. A speech is not a conversation. In a speech, one person talks while everyone listens, like at a wedding. In a conversation, people take turns and both sides can answer. So I gave a speech means you did the talking alone, while I had a conversation with her means you both spoke.