About le, this is another object, called indirect object. This OI is what recives in second place the action of the verb. And you can find it out many times asking (To who? instead of asking What?, as it was with the direct object).
So for example: Juan lee el periodico a los alumnos. (John reads the newspaper to the students).
Action: Read (leer)
Receiving the action in first place (direct object): El periodico (The newspaper).
Receiving the action in second place (indirect object): Los alumnos.
So, indirect object can be replaced for 'le' or 'les', according to the person.
In my example we would say: Juan les lee el periodico, (John reads the newspaper to them), because 'los alumnos is plural'. Now we don't have feminine or masculine, it will always be 'le or les', just singular and plural cases.
If there were only women, and instead of 'los alumnos', we say 'las alumnas', still, Juan les lee el periodico, (John reads the newspaper to them).
It will change only for singular form. Juan lee el periodico a Pedro or a Laura (John reads the newspaper to Pedro or to Laura), again doesn't matter the gender, it will be: Juan le lee el periodico (John reads the newspaper to him/her.).
And, there are cases, were both the indirect and the direct object are replaced.
In this cases, the indirect object always turns into 'Se'.
Juan lee el periodico a los alumnos: Juan se lo lee. (los alumnos turned into 'se', and periodico into 'lo', notice we don't say 'les lo lee', this is wrong)
Juan trae las herramientas para los trabajadores (John brings the tools for the workes) -> Juan se las trae.
Juan da los discos a Laura (John gives the albums to Laura) -> Juan se los da
Juan hace la comida para Pedro (John prepares the food for Pedro) -> Juan se la prepara.
Hope it's clear :)