A flight Instructor reported a NMAC with an aircraft being operated by a solo student pilot.

Narrative

While instructing my student; we were flying in a straight line and gained visual contact on another aircraft at the same altitude. The aircraft was expected to pass in front of us until; once abeam us; he took a seemingly random turn directly head on into us. This caused me to immediately take controls from my student; apply full throttle; and climb away from the approaching aircraft.When called over the radio the student claimed he was a student pilot solo and did not appear to speak English to a proficient standard. The radio calls this student made were incomprehensible and the only parts I were able to make out were 'Student pilot solo' and his tail number; Aircraft Y; a plane from a local flight school that has caused my flight school many similar problems and incidents.I believe this was a student who was sent solo too early; or who should not have been sent at all since I was questioning his ability to speak the English language. This student also seemed very lost; as he stated he was on his way to ZZZ; but was over 10 miles to the south east of the airport.He did eventually fly *near* ZZZ; where multiple other aircraft attempted to contact him because he flew dangerously close to them as well; until he realized he had climbed to above 3;000 feet; at which point he maneuvered back around 270 degrees; cut through the final approach course for the active runway (XX); then departed back towards ZZZ1.This student appeared to have lost all situational awareness; did not appear to have any idea where any traffic surrounding him was; and once again; did not seem proficient in the English language - something that is determined while filing Student pilot certificates; and I believe the honor system in this case has been taken advantage of. This student also did not seem proficient enough to solo; and had I not taken evasive action; this could have been the last flight this student; or myself; ever went on.