In ArcGIS Pro, ArcMap, and other computer software in general, use of spaces in both file names and folders may lead to unexpected behavior as some software components and tools may have difficulty accessing such file paths. In ArcGIS Pro, this may result in some of the tools running with unexpected outcomes, or receiving errors.
Due to this, as a general good practice, it is recommended to avoid using spaces when naming files and folders, and instead substituting them with underscores, for example, "separate_words", or using a technique called camelCase, which uses uppercase letters to signify individual words in the names of both files and folders connected to ArcGIS Pro and other software, for example, "iPad".
Using other special characters is generally not recommended, since they may cause similar issues, and may not be understood by the ArcGIS software or the operating system it is running on. This applies to files and folders both local to the computer being used, or being accessed remotely such as on a network drive or another server.