Recently I have been thinking if space counts as a letter? I mean In computer coding when space is in place it count as one character, but what about in real language, is it character also?
Perhaps. It is proposed in Generative Phonology that a # boundary precedes and follows every syntactic constituent in an expresssion (including the words), and this with various conventions makes ## correspond roughly to the spaces in conventional spelling. The convention is given in detail in The Sound Pattern of English.
(Personally, I don't believe it.)
In practice, no. When you do corpus linguistics and part-of-speech (POS) tagging, you consider words and punctuation marks as constituents, but not the spaces between the words.
When you consider spoken language, pauses are relevant entities, as well as fillers (like em, er), but again not the spaces that separate words.