إِذَا دَخَلَ أَحَدُكُمُ الْمَسْجِدَ، فَلْيَرْكَعْ رَكْعَتَيْنِ قَبْلَ أَنْ يَجْلِسَ
Translation: When one of you enters a mosque, let them pray two units before sitting down.
Source: البخاري ومسلم
دَخَلَ means “entered,” الْمَسْجِدَ “the mosque,” فَلْيَرْكَعْ “let them pray,” رَكْعَتَيْنِ “two prayer units,” and قَبْلَ أَنْ يَجْلِسَ “before sitting.” رَكْعَتَيْنِ is a dual form: two.
The narration teaches praying two units upon entering the mosque before sitting, commonly known as taḥiyyat al-masjid. Detailed jurisprudential exceptions and particular circumstances belong to later study; the focus here is the basic wording and order.