left
The Italian word 'sinistra' is used to indicate the direction opposite from right. It can be used in directional instructions, to describe artwork, in political contexts and more. Note that in Italian, the adjective usually follows the noun, as in 'la mano sinistra' for 'the left hand'.
The apple is on the left of the book.
This sentence is primarily used to teach the spatial sense of 'sinistra'. In this context, 'sinistra' means 'left' and helps locate the apple in relation to the book.
Should I turn left?
The question 'Dovrei svoltare a sinistra?' is often used in the context of asking for directions. Here, 'sinistra' refers to the left direction.
My left arm hurts.
In this sentence, 'sinistra' is used to indicate the left side of the speaker's body. It is common to use 'sinistra' along with body parts to specify the left side.