I
In German, 'ich' is the first person singular pronoun and is used to refer to oneself. It is the equivalent of 'I' in English. It is important to note that 'ich' is always capitalized in German, regardless of its position in a sentence.
I am learning German.
This is an example of using 'ich' (I) in a present tense sentence. 'Lerne' is the first-person singular present tense form of 'lernen' (to learn).
I have a dog.
This sentence uses 'ich' (I) with 'habe' (have), the first-person singular present tense form of 'haben' (to have). 'Einen' is the accusative form of 'ein' (a/an) used before a masculine noun, 'Hund' (dog).
I see the apple.
In this sentence, 'ich' (I) is paired with 'sehe', the first-person singular present tense form of 'sehen' (to see). 'Den' is the accusative form of 'der' (the) used before a masculine noun, 'Apfel' (apple).