If you are a fan of working with your command-line, csvkit is a great companion to do basic operations around CSV files. This includes converting files to CSV (csv, dbf, fixed, geojson, json, ndjson, xls, xlsx, sql), getting a first look at the data and generating basic stats.
Depending on the file size, you can also use it for basic file operations, like splitting data.
To install csvkit start up your command line interface and use pip:
sudo pip install csvkit
You'll find a nice beginner tutorial on the csvkit website.
Some additional notes from the makers:
Csvkit is not optimized for speed and struggles to run some commands over larger files.
Csvkit has very limited capabilities for actually editing problematic values in a dataset, since the community behind the library aspired to keep the library small and lightweight.