The word "slew" has several meanings, depending on its context.
1) In a general sense, it can refer to an abrupt change or transformation in something - for example, "the company's new policies have caused a slew of complaints from employees."
2) It can also refer to a large number or quantity of something - as in, "there has been a slew of new products released by the company this year."
3) In its most specific sense, "slew" refers to a group of animals (usually horses) being driven together.