Learn Arabic (Modern Standard): أكلنا ثم ذهبنا إلى السوق.

In Arabic, the subject is built right into the verb. The suffix نا (nā) at the end of أكلنا (akalnā) and ذهبنا (dhahabnā) is the ending for 'we' in the past tense. You don't need to use the separate pronoun نحن (nahnu) unless you want extra emphasis.

Does the base of the verb change when we add the نا suffix?

Not much! You just take the past tense base, like أكل (akala, he ate) or ذهب (dhahaba, he went), make the last letter silent (no short vowel sound), and add نا. So ذهب becomes ذهبنا (dhahab-nā).

What is the difference between و (wa) and ثم (thumma)?

While و just means 'and', ثم means 'then' or 'after that'. It shows a sequence of events with a little bit of time passing between them, which is perfect for saying 'we ate, THEN we went to the market'.

Why is the L sound missing when pronouncing السوق (the market)?

The word starts with the letter S (Seen), which is a 'sun letter'. When you add ال (al) meaning 'the' to a sun letter, the L is skipped and the first letter of the word is doubled. So, it is pronounced 'as-sūq', not 'al-sūq'.