The letter E is signed by holding up your dominant hand, palm facing out, with your top 4 fingers all touching each other and tightly curved in, while your thumb is also curved and tightly tucked into your palm, touching the tips of the fingers above.
This looks just like the small letter 'e'.
Teach your toddler the letter E sign when it is necessary to finger-spell some simple words - or the initials of objects, places, animals, or people's names. That way, your toddler slowly begins to associate the sign with the sound of the letter in a word or name.
This is a useful flash card taught best in conjunction with the other letters of the alphabet.