Yes, there is something that makes a language harder or easier to learn: how different it is from your native language in terms of sentence structure and rules.
Think of it like learning to operate different vehicles. If you already know how to drive a car, it won’t be too hard to learn to drive a semi-truck. There will still be challenges, but your brain already knows some basic things – steering wheel, brakes, gas, turn signal, speedometer.
Learning how to operate a helicopter would be a lot harder. All the buttons are in different places and your prior knowledge of driving cars is not as helpful.
So for you, the car is English, the semitruck is Spanish or French, while the helicopter is Japanese.
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