There are plenty of guides online about how to translate WordPress plugins, so here we'll just concentrate on some specific use-cases.
In general, there are 2 of them:
- you need to create the translation for another language
- you just want to change few lines of text to your liking
For both of those using language file to create a translation is the recommended way, as it will allow to preserve those changes after future updates of plugin. Also it won't need any programming skills - you won't need to go into the code.
On how exactly to create it please refer to one of the guides, for example:
In short, you'll just need to download some software and follow the instructions.
For example, Poedit is quite popular and cross-platform, so you could easily use it:
Another case is WPML support - you'll find that some of our plugins already support it, while for others the support is coming in future. But in general all our products will support WPML.