"Good soup is tasty."
Translation:Goede soep is lekker.
Soep has article "de" - de soep. If there is no article in the sentence ..... warm soup is tasty, you have to use -e in the adjective. In this case "warme soep. If it was e.g. good girl, you would say "goed meisje". The girl has the article "het". In this case you can miss the -e. So... if there is no article in front of the adjective, you just have to know if the noun is "het" or "de". If "het", adjective is without -e. If "de", adjective is with -e.