It means to flirt with someone, to try to charm them, or to make a pass at them.
The expression emphasizes the use of flattery or sweet talk, often in a playful or romantic way. It can be used in both a positive and negative sense, depending on the context and the intention behind the "cantada."
Here are some examples:
* Positive: "Ella es muy bonita, voy a echarle la cantada." (She is very beautiful, I'm going to flirt with her.)
* Negative: "Ese chico siempre está echando la cantada a las chicas." (That guy is always flirting with the girls.)
The use of "echar la cantada" often implies a casual and lighthearted approach to flirting. It's not necessarily a serious romantic pursuit, but rather a way to express interest and initiate a conversation.