specification reads as follows:
The translate (x, y) method must add the translation transformation
described by the arguments to the transformation matrix. The x
argument represents the translation distance in the horizontal
direction and the y argument represents the translation distance in
the vertical direction. The arguments are in coordinate space
units.
see the original : http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html # dom-context-2d-translate
translate (x, y) function is the level of the entire canvas to move the x distance, y distance of vertical movement.
canvas is (0,0) as the default origin, the origin of the upper left corner of the screen by default; by translate (x, y) the point (x, y) as origin.
Note: It is at the origin, respectively, on the basis of the offset x and y.
example: if the fall on the origin (1,1), then translate (10,10) is at the origin (1,1), respectively, on the basis of the x-axis, y axis 10, the origin becomes is (11,11).