Learn German: Ich packe ein Hemd und eine Brille. - I am packing a shirt and a pair of glasses.

Hemd (shirt) is a neuter noun (das Hemd). In the accusative case (which we use for direct objects that are receiving an action, like being packed), the indefinite article for neuter nouns stays exactly the same as its basic nominative form: ein. Only masculine nouns change their article to einen in the accusative.

Does the article for Brille change in the accusative case?

No, it stays exactly the same! Brille is a feminine noun (die Brille). Just like neuter nouns, feminine nouns keep their basic indefinite article (eine) when they are the direct object of a sentence.

The English translation says 'a pair of glasses', but the German just says eine Brille. Are glasses singular in German?

Yes! In English we treat glasses as a plural object ('these glasses are dirty'), but in German, die Brille is a singular feminine noun. If you wanted to talk about multiple pairs of glasses, you would use the plural form die Brillen.

Why is the verb packe and not packen?

packe is the conjugated form for Ich (I). When Ich is the subject doing the action, you drop the -en from the dictionary form of the verb (packen) and add an -e to the end.