Li is a Mandarin word that can mean a great deal of things. Not in the sense of the syllable Li has many homonyms, but that the word Li, which basically means uprightness, has many different interpretations.
One of the earliest meanings of Li was ceremonies, in the sense of rituals and structures that people went through at specific times and for specific reasons. From there, the word developed a more general meaning, that can mean moral law, universal principles, or justice.
In Confucian thought, li, the ability to understand the universal moral law, was a virtue only next to ren, or the ability to act humanely.