Why doesn't mag follow the rules? shouldn't it be "Sie magt Manner" for she likes men and "Sie magen Manner" for They like men?
because it's a modal verb. the original form of the verb is mögen = to like. and for the first, second and the third person singular the "ö" turns in to "a". that is why it is ich mag, du magst, er/sie/es mag, wir mögen, ihr mögt, sie/Sie mögen. hope that this was helpful
If talking about human relationships, 'to love' would certainly be to strong. It might work in constructions like 'she loves tea' - 'Sie mag Tee sehr gerne'. However, even then I'd prefer to translate 'to like' to 'mögen' and 'to love' to 'lieben'.
How again would I know if its "They like men" or 'She likes men"? I thought if the noun was plural then 'Sie' is 'they'..
One can tell based on the verb. If it is "they", the verb will usually end in n. So, they like men would be "sie mögen Männer" whereas if it is she the verb will usually end in a t, though with some verbs like this one, the form is different; she likes men is "sie mag Männer".