How to read a distance on a survey (house)

Almost. Except that .3 of 12 is 3.6 not 4. 

Measurements of surveys are often in Decimal Feet. For example 2.5' is two and a half feet, not 2 feet 5 inches, which would be notated as 2'5".

In your case 19.3' means "nineteen point three feet". Point three of a foot is 3 19/32" inches. So your distance is 19' 3 19/32".