anti-lock?

[silveralero88]

so today i was at work.. i use my car a lot for what i do at work.. and i stopped to use the bathroom. i turned my car off... then when i came back.. it wouldnt start.. i figured it was the battery.. jumped it and it works.. but this anti-lock light came up now.. was wondering whats it for.. i dotn even have the car manual.. the previous owner threw it out.. so im clueless here. and my car still dies after i turn it off.. i think i will have to buy a new battery... but the antilock still bug me.