What is an IRA and why shold I contribute

Ok, so i am 54 years old, wanting to pay off debt, and start saving for kids college and retirement. I know its late but i am done not being bettter with my finances. I am hearing about I should consider conributing to an IRA... how does this benefit me. I really dont know anything about finances and the more help i get for trying to understand what things are the better. Please help me understand what an IRA is and how it will help me later in life if I open one now and start contributing