Learn Hardcore Latin: Fortasse discipulus in horto sedet. - Perhaps the student sits in the garden.

1st sg.: sedeō – I sit
2nd sg.: sedēs – you (sg.) sit
3rd sg.: sedet – he/she/it sits
1st pl.: sedēmus – we sit
2nd pl.: sedētis – you (pl.) sit
3rd pl.: sedent – they sit

In English: “Perhaps the student is sitting in the garden.”
In Latin, fortasse is usually placed near the beginning of the sentence, but it can move:
- Fortasse discipulus in horto sedet.
- Discipulus fortasse in horto sedet.

All of these still mean something like “Perhaps the student is sitting in the garden.” The position changes emphasis slightly, but not the basic meaning.

Why is discipulus the subject of the sentence?

Latin shows the subject mainly by case endings, not by word order.

Discipulus ends in -us, which is the usual nominative singular ending for a masculine noun of the second declension.
The nominative case is normally used for the subject of a finite verb.

The verb sedet has a third-person singular ending (-t), so it matches discipulus:

discipulus = he (the student)
sedet = sits / is sitting

Because they agree in person and number, and discipulus is nominative, we identify discipulus as the subject.