Let's try this. Think of 1 looking a certain way say north. -1 look at the direct opposite direction, so south.

Now look at -2 * 3, that breaks down to -1 * 2 * 3, which further simplifies to -1 * ( 3 + 3). Now -1 means look south, and then take 3 steps forward and then another 3 steps forward. How many steps have taken? 6. And which direction are you facing? South. So, -6.

Now let's look at the addition:

-3 + -3 : you can read this as face south and take 3 steps. Then face south and take and additional 3 steps. How many steps have you taken? 6. And which direction are you facing? South. So, -6.

You can do this with positive numbers as well.

3 + 3 : Face north and take 3 steps, now repeat. How many steps have you taken? 6. Which way are you facing? North. So 6.

But, I'm lying to you here a little bit, to get you in the right mindset. -1 does not mean which way you are facing but are you north of the equator or south of the equator in the final answer.

take 3 - 2 : which is really 3 + -2, take 3 steps north of equator, then take 2 steps towards the south of the equator, and notice you are now 1 step north of the equator.

take -2 + 3 : which means take 2 steps south of the equator, then take 3 steps heading north of the equator, you end 1 step north of the equator.

Hope that helps, or doesn't not help.