must practiceต้อง means “must” or “need to,” while ฝึก means “practice” or “train.” The phrase can refer to practicing a skill or undergoing training, including military training.
TH: ถ้าอยากพูดภาษาไทยได้ดี คุณต้องฝึกทุกวัน
EN: If you want to speak Thai well, you must practice every day.