Learn Icelandic: Ég tek pakkana. - I am taking the packages.

The base word is pakki (a package). Because it is the direct object of the verb taka (to take), it goes into the accusative case. The accusative plural form is pakka (packages). To say the packages, we add the definite suffix -na, making it pakkana.

Why does the definite article ending look like -na here?

In Icelandic, the definite article (the part meaning "the" that attaches to the end of the noun) changes depending on gender, number, and case. For masculine nouns like pakki in the accusative plural, the definite suffix is always -na.

How would I say "I am taking packages" (without "the")?

You would drop the -na ending and just use the bare accusative plural form, which is pakka. The sentence would simply be Ég tek pakka.

The English translation says "am taking". Where is the word for "am"?

Icelandic doesn't use a separate "am doing" form like English does. The simple present tense verb tek covers both "I take" and "I am taking". You figure out which one makes the most sense from the context!