A/V is just an abbreviation for Audio Visual. It generally means a method of connecting an external piece of televisual kit to another piece of televisual kit. As almost all AV connectivity in the UK is done primarily by scart (or at least was until HDMI became widespread) it was common for all electrical equipment with scart connectors to label them as AV1, AV2 etc. Quite often you will find non-scart connectors labelled AV3, AV4 and so on. I have a Toshiba LCD where AV1 and AV2 are both scart inputs, AV3 is used for either component or composite connectivity.
The connections you are describing are known as composite connectors - red and white for audio, yellow for video. As long as the source has composite out, and the target has composite in, these will work okay. But, they are generally considered not as good as scart connections because they cannot transmit an RGB signal, only a (surprise surprise) composite signal.
Signal quality (from best to worst) is normally considered to be:
HDMI
Component
RGB
S-video
Composite
RF.
So, the A/V that you are used to (composite) is often considered two layers lower down the quality scale than RGB scart.
It will still work fine. In fact, if that is all you have ever been used to, you will not notice anything wrong with it at all. It is only if you see the same transmission being played back via RGB that you might then want to upgrade your DVDR to something that has RGB scart output on it.