وَإِنْ قَصَّ أَقَلَّ مِنْ خَمْسَةِ أَظَافِيرَ فَعَلَيْهِ صَدَقَةٌ
Translation: If he clips fewer than five nails, charity is due.
Aqalla min khamsah is a precise quantitative expression: one, two, three, or four nails. The text prescribes sadaqah for this category.
This is a compensation threshold, not a permission to trim a small number of nails while in ihram.