Media mañana depends on the one who is speaking, but it's between 10 and 12 h (12 h. is "mediodía"). For instance, I take my second breakfast around 10 or 10.30 h in the morning (the first is around 7 h.). Usually we say: voy a tomar un café (we're working at that time). I work from 8 to 15'30 h., so I can't stay so long without eating something. I take my breakfast at home and later at work, a media mañana (between 10 and 12, more or less), I take a coffe or another breakfast (it's the same)
