The Spanish preposition "con" means "with".

Let´s see some of its common uses:
Yo quiero ir al partido de fútbol con ellos.
I want to go to the soccer game with them.
Trabajo con los caballos.
I work with horses.
Hablé con el director.
I spoke with the principal.
¿Quieres ir al partido de fútbol con nosotros?
Do you want to go to the soccer game with us?
Yo iré al partido de fútbol con ustedes mañana.
I will go to the soccer game with you all tomorrow.

However, you cannot use "con" in the same way to say "with me" and "with you"

Incorrect!
con yo
con tú

Correct
conmigo - with me
contigo - with you

Example:
¿Quieres venir conmigo? - Do you want to come with me?
Venga conmigo. - Come with me.
¿Quiénes irán contigo? - Who is going with you?
Yo no puedo ir contigo. - I can't go with you.