That's weird, when I move onto the word schlafe, it appears "(we, they) sleep"...
How do you know which ending, if it's something other than a human doing the action? Like, if a cat or bird is sleeping?
Every conjugation is based on who is doing the action. For one "thing" (a cat, for example) would be considered as one person doing the action, and would be conjugated accordingly (using the er/sie conjugation), based on the gender of the noun (die Katze schläft for the hypothetical cat). More than one thing (say two cats or a cat and a dog together) would use the informal plural conjugation (sie) (die Katzen shlafen).
Am I the only one who thinks that is hard to pronounce this? I mean, changing the type (I really don't know how to explain) of pronunciation from the 'ch' in "Ich" to the "sch" in "schlafe"?
In German the same word is used for simple present and present continuous. So 'We swim' and 'we are swimming' would both be 'Wir schwimmen'
Ich schlafe Du schläfst Er/sie/es schläft Wir schlafen Ihr schlaft Sie/sie schlafen
This is getting more confusing now. The first one is schlaft and why will this one be schlafe?
Well it might be because of Ich, which is singular. Just like Ich trinke ( I am drinking).
Schlafe is to sleep, but is there also a word called Schlafen? If so, in what context is it used?
NO, Schlafe is indicative. "Ich schlafe". Schlafen is infinitive, so in english it would be like saying "I want to sleep" as opposed to "I am sleeping"
So just to clarify, you are saying that the word Schlafen does exist, but it doesn't fit in this context? Or does Schlafen not exist at all?
CLARIFICATION: Schlafen is used in the English sense "to sleep", while Schlaf[e][st][t] is used in our sense of "I/you/he sleep[s]"