"There is still a little milk in the bottle."
Translation:Il reste un peu de lait dans la bouteille.
Please don't repeat your questions and be a little patient: we are not all on the same time zone.
"du lait" uses the partitive article for undefined quantities of uncountable things.
But here, you have to use "de" instead of "du" (or "de la") because of "un peu de", which is a prepositional phrase expressing a quantity, like: plus de lait, beaucoup de lait, moins de lait, autant de lait, etc.
There is another case where "de" replaces "du" (or "de la"): negative sentences like "il n'y a pas/plus/jamais de lait".