He is the fifth letter of the Syriac abjad, with the numeral value five. It writes the consonant h. It joins only to the right, so a letter following it starts a fresh connected group.
In the Estrangela hand, the oldest of the three, he is a small closed loop, and it is drawn quite differently in the western Serto hand and in the eastern Madnhaya hand. That spread is worth stating plainly, because it is easy to meet one hand first and take it for the alphabet. Estrangela is the classical book hand from which both later hands developed; Serto belongs to the western churches and Madnhaya to the Church of the East. All three write the same twenty-two letters and this entry is for the letter, not for a hand.
Its name continues the Northwest Semitic word usually glossed as a window. The gloss reconstructs the sign of the older linear alphabet rather than describing anything in the Syriac shape, which rests on the name alone for the connection.
He does a great deal of grammatical work in Syriac. It writes the third person pronominal suffixes, so the letter that ends a word often carries the word for his or her, and it opens the demonstratives. A learner therefore meets he at both ends of words very early, which is one reason its distinctive shape in each hand is among the first things anyone recognises.