In Linux Mint 19 there isn't default shortcut for changing language layout so you will need to add a custom one in order to change from one language keyboard to another. Adding custom language shortcut is available by:

  • Menu
  • Preferences
  • Keyboard (or search in the menu)
    • another way to access it is by language icon - in the up corner, then Keyboard Settings and finally Layouts tab)
  • Press button Options.. in the right bottom corner
  • Switching to another layout
  • Select your preferred one
    • I like to use: ALT + SHIFT
  • Close

Linux Mint 19 change language

From the same place you can change many other settings like Caps Lock behavior, Numeric Keypad layout, Alt/Win behavior and so on.