Unicode, a braille cell does not have a letter or meaning defined. For example, Unicode does not define U+2817 ⠗ BRAILLE PATTERN DOTS-1235 to be "R"....

Braille characters. The Braille pattern dots-1235 ( ⠗ ) is a 6-dot braille cell with dots raised, or an 8-dot braille cell with raised. It is represented...

Braille pattern dots-124 ( ⠋ ) is a 6-dot braille cell with the two top dots and middle left dot raised, or an 8-dot braille cell with both top dots and the...

and ⟨s⟩. The name of the letter in Latin was er (/ɛr/), following the pattern of other letters representing continuants, such as ⟨F⟩, ⟨L⟩, ⟨M⟩, ⟨N⟩,...