This is the 92nd most frequent Hindi word.
लड
The Hindi word "लड़" (laṛ) means "to fight" or "to struggle" in English.
Here, 'लड़ा' (lad) is used as a verb in past tense indicating a struggle or fight for a cause.
वह अपने अधिकारों के लिए लड़ा।
He fought for his rights.
Here, 'लड़कियां' (ladkiyan) uses 'लड' as a root combined with a suffix to denote plural of 'girl', contextualizing the term in a noun form.
लड़कियां उस प्रतियोगिता में भाग लेंगी।
The girls will participate in that competition.
In this sentence, 'लडाई' (ladaai) is derived from the root 'लड' to mean 'fight', contextualizing the term in a noun form signifying an act of fighting.