An approximator is something which approximates something else.

Standard Hindi and most other vernaculars do not differentiate between /v/ (voiced labiodental fricative) and /w/ (voiced labiovelar approximant). Instead, most Indians use a frictionless labio-dental approximant for words with either sound. So wine is pronounced like vine.

Yes, the letter "W" is considered a soft sound. It is a voiced labiodental approximant, pronounced by bringing the lips close together without contacting them.

In Tamil, the word "zha" is pronounced as a retroflex fricative sound similar to the English "r" sound. In Malayalam, it is also pronounced as a retroflex fricative, but it can vary depending on the dialect, and sometimes it may be pronounced as a retroflex liquid or a retroflex flap.