捷 is a bound form (b.f.) that appears only as part of compound words. It has two main senses: a sense of 'victory' or 'triumph' (as in 捷报 'news of victory', 大捷 'great victory') and a sense of 'swift' or 'quick' (as in 捷径 'shortcut', 敏捷 'agile'). As a bound form, you never use it alone; it always attaches to another morpheme.