Translation:They fill their bags with bananas and peanuts.
In short, it's when a preposition (or more!) attaches itself to a verb, such as in "stand up for" or "get away with."
Germanic languages do this all the time, and English is part of the German family. You've probably heard grammar nazis tell you not to end a sentence with a preposition. That "rule" only came about because Latin can't end sentences with prepositions. Technically, neither can English, because the preposition used in phrasal verbs is part of the verb, just as much as any helping verb.
Another way to look at the sentence is to find out what the "preposition" is modifying, since prepositions can only modify nouns. If there's no noun to modify, you're looking at a phrasal verb!
If you check this comment for phrasal verbs, you'll find some interesting quirks, such as how a word can be slotted in between the main verb and the preposition word. This splitting of the verb is similar to a split infinitive, which incidently also can't be done in Latin.
Now that I'm looking at the sentence structure, it's possible dengan modifies tas. And although "fill with" is a phrasal verb, the sentence here seems to be verb/object/preposition. But I'll keep a lookout for this in the future!
World literally means bean but is also used for some of nuts. For example peas (kacang hijau = 'green beans'), kidney bean (kacang merah = 'red bean'), cashew (kacang mete). If 'kacang' is without any aditional word, usually points on peanut. Peanut full name is kacang tanah.