Rashi on Numbers 22:25/רש"י על במדבר כ״ב:כ״ה

1וַתִּלָּחֵץ — the Niphal form denotes that SHE PRESSED HERSELF.

2וַתִּלְחַץ — the Kal denotes that SHE PRESSED something else — viz., את רגל בלעם BALAAM’S FOOT.