This is the 4018th most frequent Arabic word.
تكفي
"تكفي" means "sufficient" or "enough."
Here, تكفي means 'is sufficient' to convey adequacy.
تكفي هذه الكمية لإعداد الحساء.
This amount is sufficient for making the soup.
In this sentence, تكفيك refers to whether something suffices for someone.
هل تكفيك هذه النقود لدفع الفاتورة؟
Are these funds enough for you to pay the bill?
Here, لا تكفي negates sufficiency to indicate inadequacy.