I will not understand these phrases until you start teaching me when to use собака, собаку союаки in conjugation phrases singular and plural.
Read the notes for each unit. They explain about Russian cases, plurals, verb conjugations, etc. In this sentence you must use the the Accusative case.
If i used word PES instead od SOBAKA.. how would the sentence look like?
You probably shouldn't, but if you want, «я хочу пса».
What's the difference between пес and собака?
"Пёс" = "dog" or "he-dog" (male dog),
"Собака" = "dog".
Why I cannot say собака, или собаки?
Read the notes for the lesson. They explain about Russian case. In this sentence you must use the Accusative case.