You will earn between €800 EUR to €1000 EUR per month depending on the region as a stipend, which is relative to the cost of living of the location where you are placed. The stipend is equivalent to a very competitive Spanish wage. The cost of living in Spain is drastically cheaper than it is to live in North America, and you will have more than enough money to live off of with what you will be earning.
The monthly stipend will come directly from the school or the Spanish regional government, and all questions should be directed to them. The stipend will typically arrive the first few days of the following month and is nonnegotiable. For example, the stipend for the month of October will arrive the first few days of November, and the stipend for November will most likely arrive the first few days of December.