i wish to clarify:
habt = ihr habe = ich haben = plural subjects hat = sie/es/er
am i correct?
Yes, you're right.
haben (to have)
ich habe (I have)
du hast (you [singular, informal] have)
er/sie/es hat (he/she/it has)
wir haben (we have)
ihr habt (you [plural, informal] have)
sie/Sie haben (they/you [sgl. + plural, formal] have)
How do you refer to a verb in german, as in english one would say, for example: to eat, to read, to walk...?
I think they end in EN: lesEN, habEN, essEN,... (some don't : seIN, for example)
Look at the verb form.
sie hat = she has
sie haben = they have
1.) From the verb, see my list above.
Sie hat Wasser . = She has water.
Sie haben Wasser. = They/you (formal) have water.
2.) From the capitalisation - only "Sie = you (formal)" is capitalised if it appears in the middle of a sentence.
3.) From the context.
No, because that would indicate that she is drinking water or planning to drink water. The German verb "haben" does not mean that someone is eating or drinking something.
Because of the verb.
1) sie hat = she has
3) Sie haben = you (formal) have
4) sie haben = they have
Why is this not: "Sie hat das Wasser"? Wasser is neuter and here it is used in accusative. I thought that singular nouns MUST have either definite or indefinite article. What am I missing here?
That's mostly true for countable nouns. (With exceptions at least for professions and roles, as you will learn later in the course, e.g. Tom ist Arzt "Tom is a doctor".)
But Wasser is a mass noun, an uncountable noun, and so it doesn't need a determiner in the singular.