SIM card: access to internet/maps

Trishia, A SIM card is your connection to your phone provider. Think of it as the same as plugging your home phone into the socket. It defines who you pay bills to, and what your phone number is.
Your phone provider (via your SIM card), gives you a phone service, text message, and optionally data (internet access etc.)
WiFi is a totally different thing. It is an alternative way to access the internet. It does not go through the SIM card, and your phone provider does not charge you. But it only works in places you have WiFi, and you usually need a password.

If you have bought a SIM card without data (unlikely) you can only access the internet (Google etc.) when you are in a WiFi area. But, there are plenty of mapping services you can use "off line", without data access or WiFi. You just need to download the App when you have data or WiFi.
I recommend City Maps 2 Go.

I use CityMaps2Go Pro and find it very workable. But you need to download not only the app but also the maps for the specific cities or areas you're visiting. Once you have them, they will be available even if you don't have access to Wi-Fi. And usually the app will be able to place you on the map by using a GPS satellite (no Wi-Fi needed). I say "usually" because I sometimes had difficulty in historic districts with narrow streets and rather tall buildings.

If you download the maps for your area when you have wifi, you can access them offline. If your GPS is turned on it will plot your location on the map.

Thanks for the suggestions. I downloaded City 2go and I am at least finally heading in the right direction!