The meaning of the word "thaw" is similar to "melt". But when something melts, it means that that thing turns into a liquid:

The ice is melting.

Compare this with "thawing", which also means to become unfrozen. However, when something "thaws", it doesn't turn into a liquid. Instead, it just becomes softer:

The chicken is thawing.

We'll start preparing for our garden when the ground thaws in early spring.