With this picture in mind where a hypothesis has signicant level of 10%. Where do we reject the value?

So 10% is 1,645. The standard normal distirbution on the picture is symmetrical, so on the left side it is -1,645 while on the right side it is 1,645. The middle part or the blue area is the non-rejection area. So if the value is inbetween those values it is not rejected, but if it is higher than both -1,645 or 1,645 it is rejected.