I extracted RNA from different cell lines, an I want to perform reverse transcription and then PCR. To get good results, in which range should the absorption ratios 260/280 nm and 260/280 nm be? And what is the idea behind measuring those ratios?

I got for the 260/280 ratio values from 2.1 to 2.13 and for the 260/280 ratio values from 0.98 to 2.01. Are these values acceptable, and what information can I gain from them?