Socio-economic factors, also widely spoken of as SES (socio-economic status), is basically two things: (1) Financial resources or income, and (2) level of education.
Notice how poor and uneducated people will win the lottery but still don't change. They spend all the money frivolously. Some still get in trouble with the law. They often end up in the same circumstances (or worse ones) than before they won. This is because SES is not only about money, and many poor people are not poor only because they caught a tough break in life. Ever notice how highly educated people act differently and make different choices even though they may be just as poor as their peers?
Now, SES is highly correlated with things like IQ, likely hood to go to college, academic success, crime, race, health disparities, drug use (especially certain drugs of choice)... the list grows with every piece of research. In fact, many of the "racist" things our society touts are actually correlated with SES and not race at all (unfortunately race is correlated with SES too. This might be because harsh racist histories have crippled families and subsequent generations don't often grow up to increase their level of SES. The cycle goes on and on).