Basically, an INTER is a period in the forecast where the weather is expected to change quite bit, for durations less than 30 mins.
In this TAF, the INTER is saying between 0900UTC and 1600UTC on the 12th, the weather is likely to change to variable winds (changing directions) with a speed from 15, gusting to 25knots. Visibility will be reduced to 3000 metres in showers of rain, and clouds will be broken (7 oktas) at 800 feet.
So basically, it's a good representation of the weather in Melbourne most day
