Learn German: Sie lacht oft. - She laughs often.

We look at the verb! The verb lacht ends in -t, which is the matching ending for er, sie (she), and es. If Sie meant 'they' or formal 'you', the verb would have an -en ending, making the sentence Sie lachen oft.

How do we build the word lacht from its dictionary form?

The base verb is lachen (to laugh). Because it is a regular verb, we drop the -en to get the stem lach-, and then add the third-person singular ending -t to match sie (she).

In English we can say 'Often she laughs'. Can I say Oft sie lacht in German?

No, because German statements strictly follow the V2 rule. This means the main verb (lacht) must be the second building block in the sentence. If you want to start with Oft, the verb must come right after it: Oft lacht sie.