You can translate the theme into a single language using the free version of PoEdit: http://poedit.net/. To translate into multiple languages you can use WPML: http://wpml.org/. There are three sets of language files, one set for the theme, one set for the booking plugin, and one set for the shortcode plugin.
Theme language files are stored in:
wp-content/themes/sohohotel/framework/languages
Booking plugin language files are stored in:
wp-content/plugins/sohohotel-booking/languages
Shortcode plugin language files are stored in:
wp-content/plugins/sohohotel-shortcodes-post-types/languages
You can open the above mentioned files in PoEdit and make your translations - after that save the language files in the same folder you got them from. It's important to note, theme translation files should be same as xx_XX.po where xx_XX is the language, e.g. fr_FR.po for French. But plugin language files should be saved as sohohotel_booking-xx_XX.po. After translating in WordPress go to Settings > General and set Site Language as your translated language.
WPML has in depth documentation here: https://wpml.org/documentation/, they also have a great support forum here: https://wpml.org/forums/forum/english-support/.
Go to "WPML > Multilingual Content Setup" in the "Custom posts" section set "Bookings" to "Do nothing"