"练习剑术" can be translated into English as "practice swordsmanship" or "practice fencing (if referring to a specific style like Olympic fencing)".
Swordsmanship is a broader term that encompasses various traditional or martial arts-based sword techniques.
Fencing typically refers to the modern, sport-oriented form (e.g., foil, épée, sabre), but can also be used colloquially for sword practice in some contexts.
For a more literal or traditional context (e.g., kendo, historical European martial arts), "practice sword techniques" or "train in swordsmanship" might also work.
Example:
He practices swordsmanship every morning. (他每天早晨练习剑术。)