The term "sweetheart" can have multiple meanings depending on its context.
In a romantic or affectionate sense, it refers to someone's beloved or darling, often used as a term of endearment between partners in a relationship. For example, one might say "my sweetheart and I are going out for dinner tonight."
It can also be used more broadly to refer to anyone who is particularly kind, helpful, or generous - someone you feel grateful towards or appreciate deeply. An example of this usage could be: "My neighbor is such a sweetheart; she always helps me with my gardening!"
In some cases, the term can also be used in a more general sense to refer to something that is particularly pleasing or delightful - for instance, someone might say "this cake is just like grandma's recipe: it's such a sweetheart."