This is the 1654th most frequent Arabic word.
الوحيدة
"The only" or "the lone."
In this sentence, "الوحيدة" is used as an adjective describing the exclusive quality of the subject 'mother' as being the one person who understands the speaker.
أمي هي الوحيدة التي تفهمني دائمًا.
My mother is the only one who always understands me.
Here, "الوحيدة" describes the isolation or singularity of the horse, emphasizing its exclusivity as the only animal in the field.
كان الحصان الوحيدة في الحقل طوال اليوم.
The horse was the only one in the field all day long.
In the sentence, "الوحيدة" functions to highlight the uniqueness or singular nature of the event, mentioning it as the sole occurrence.