If you never learn about scale map here is the simple explanation. Map is a projection of the earth into a flat two dimensional plane.
When we say scale 1:1 the meaning is 1 centimeter in the real ground is corresponding to 1 centimeter on the map, 1 inch on the map is equal to 1 inch on the map. The unit is not important. Map scale is using relative unit that you can use any distance unit (inch, cm, m, yard, km, mile, nautical mile etc.) to get the same scale.
Scale 1:100,000 have meaning that 1 cm on the map is equivalent to 1 km on the ground. Using this scale, if the diameter of your city is about 20 km, you may print the city map on a piece of A4 paper (29.7 cm by 21 cm).
Architects, mechanical engineers and civil engineers usually use 1:10 or 1:20 for detail construction drawing and 1:100 or 1:500 for site plan. To see your neighborhood in quite detail, you may use scale 1:500 to 1:1000. To see your whole city in a piece of A4 paper, you may use scale about 1:10,000 to 1:100,000 (depending how large is your city area).
Preferable reference for this tutorial is
Teknomo, Kardi (2015) Introduction to GIS. http:\\people.revoledu.com\kardi\ tutorial\GIS\