The notes of Esus2 are E, F# and B. E is the root, F# the second and B the fifth. Said aloud, its notes are E, F sharp and B.
String by string, low to high, it plays E, B, F#, B, B and E. B appears three times in the main shape, and it is the chord's fifth. The lowest and highest notes are both E, two octaves apart, on strings 6 and 1.
The open strings add notes to Esus2 too. String 6 gives E, string 2 gives B and string 1 gives E. Your hand covers three frets, from 2 to 4. There is one more position, starting at fret 7.
E is very close. You only move strings 4 and 3. Esus2 and B have F# and B in common. B shares three positions with this shape.
Esus2 belongs to ten keys. In E major it is the Isus2, in A major the Vsus2 and in B major the IVsus2. The rest appear in the key list.