Ich bin dreizehn Jahre alt = I am 13 years old.
" Ist der Junge schon dreizehn" is the expression used.
Ich bin fünfundzwanzig Jahre alt (fünfundzwanzig is spoken as "FOON-FUND-ZVAN-ZIG)
"I'm ... years old" is an English equivalent of "Ich bin ... Jahre alt."Specifically, the subject pronoun "ich" means "I." The verb "bin" means "(I) am." The neuter noun "Jahre" means "years." The adjective "alt" means "old."
Wie alt bin ich? = how old am I? (pronounced "Vee ahlt bin isch?") Wie alt bist du? = how old are you? (pronounced "Vee ahlt bist doo") Ich bin _ Jahre alt = I am _ years old. (pronouced "Isch bin _ yahreh ahlt")
"Ich bin 34 Jahre alt."
you have to say;Ich bin sechzehn Jahre alt.
Ich bin 12 (zwölf) Jahre alt. or simply: Ich bin 12 (zwölf).
I am 10 = Ich bin zehn I am 10 years old = Ich bin zehn Jahre alt
"Ich bin ?? Jahre alt" is the expression in common usage.
Ich bin drei Jahre alt
I don't know what szejten is. It's not German, but Jahre alt just mean years old: I am 20 years old. (Ich bin 20 Jahre alt)
You probably mean "Ich bin vierzehn Jahre alt", which translates as "I am fourteen (years old)". Does that make sense in the context you heard/read it?