Yes you can drink condensed milk.
Condensed milk is just milk that has gone through a processed to condense it and also it usually has sugar added to sweeten it.
You can mix some water with the condensed milk and then stir the condensed milk up and have some sweet tasting milk.
I do this myself and I love the Condensed Milk as it's very sweet.
When I want to drink some condensed milk I pour a little bit of the condensed milk into a cup and then add some cold water.
Then I stir the water condensed milk up to mix it with the water and I have a sweet tasting milk.
I also sometimes add condensed milk to my coffee which makes it taste good too.
Another thing I do when I drink tea is to add some condensed milk to my hot tea.