This is the 3973rd most frequent Russian word.
ибо
"For" or "because" (used in formal or literary contexts).
In this sentence, 'ибо' is used to introduce the reason or explanation for the preceding statement.
Мне нужно уйти рано, ибо мне нужно готовиться к экзамену.
I need to leave early, for I need to prepare for the exam.
Here, 'ибо' is providing the rationale behind the speaker's joy.
Я рад, ибо сегодня светит солнце и тепло.
I am happy, for today it is sunny and warm.
In this context, 'ибо' links the actions to its underlying cause, emphasizing the importance of the material.