Seen سِين
Like 's' in sun, a light whistle. Three teeth.
Its shapes
Trace it with your finger
👄 Where the sound comes from
The tongue · س
Most letters are made by the tongue touching or nearing the roof of the mouth or the teeth.
⚖️ Don't mix it up with
- ث
Thaa
Like 'th' in thin: tongue tip just out between the teeth. Three dots. - ص
Ṣaad · heavy
A heavy 's': back of the tongue raised, mouth full.
Say Seen and the other letter one after the other, slowly, and feel the difference. A teacher can check you.