"I am at home."
Translation:Ego domi sum.
No. Latin is a pro-drop language. All of the following are perfectly correct, but in descending order of preference:
Ego domi sum.
Ego sum domi.
Latin is an SOV language with reasonably flexible syntax, meaning other permutations of that order are perfectly acceptable. However, because "esse" (to be) is a verb of state and especially since the 3rd person pronouns is/ea/id are somewhat weak and are also used as demonstratives, when you're saying "...is [NOUN]", it's better to use SVC (C for complement) to avoid misinterpretation.
In other words, "She is a sister" can certainly be "Soror est" or "Ea soror est", but it's too easy to interpret that as "A/the sister is" or "This sister is" and therefore "Ea est soror" would be preferable to ensure clarity. You could say "Soror ea est", but that shifts the focus, a bit like the difference between "SHE is a sister" and "She is a SISTER."