Learn Arabic (Modern Standard): قرأتم قصة ممتعة.

The suffix ـتم (-tum) at the end of the verb makes it the past tense for 'you' plural. You use this for a group of males or a mixed group. If you were talking to just one man, you would use the singular suffix ـتَ (-ta) to make it قرأتَ.

The English translation says 'read'. How do we know this is the past tense rather than the present tense?

In Arabic, past tense verbs are formed by adding suffixes to the end of the word, exactly like the ـتم ending we see here. Present tense verbs use prefixes at the beginning. Because the ending changed rather than the beginning, we know it happened in the past.

Why does the word for 'interesting' (ممتعة) end with the letter Taa MarbuuTa (ة)?

In Arabic, adjectives come after the noun and must match its gender. The word for story (قصة) is feminine, which we can tell by its ة ending. Therefore, the adjective must also be feminine, so we add a ة to make it ممتعة.

What is the symbol on top of the middle Alif in قرأتم?

That is a Hamza (ء), representing a glottal stop (a brief catch in your throat, like in the English phrase 'uh-oh'). The base verb is قرأ, ending with this sound. When we add the ـتم suffix, we keep that distinct stop before the ending: 'qara-tum'.