A community member asked this question in a private message. I'll answer here because someone else might have the same question.
Knowledge of object-oriented programming will be a great benefit, so any object-oriented language will do.
However, 1C:Enterprise script is much simpler than any object-oriented language because you do not have to write new classes. The only thing you need to understand is the concept of objects (entities that have methods, attributes, and constructors). That simple!
Actually, you do not even need to learn any programming language before 1C:Enteprise script, it can be your very first programming language. 1C:Enterprise Practical Developer Guide is a good tutorial for people making their first steps in learning 1C:Enterprise application development, and it even works for those who never studied programming before.
In my opinion, most important and useful would be to know SQL. Many difficult algorithms are written in this language in 1C:Enterprise applications. In 1C:Enterprise used special syntax of SQL that is very similar to standard SQL (like SQL/89) but only with read operations like SELECT.