Encantado de conocerlo I found this is Spanish, and Baidu translated it as "Nice to meet you". Then I guess the preposition "de" here follows the adjective "encantado" to express the reason.
In addition, you can also indicate the source of people or things: Soy de China. I come from China; Can express the characteristics of someone or something: la mesa de escribir desk; It can also express a comparative relationship. My book. As slang.
The above answers are for reference only. I wish you a happy study.