This page of the Watch Dogs Legion guide describes how to get money and how you can spend it.
How to make money?
You can acquire ETO - the in-game currency - in several ways. The simplest (and involuntary) is to complete missions. For each completed mission you receive a certain amount of money. The mission panel will tell you exactly how much.
Deliveries are unique missions focusing solely on earning money. In the game you will find special machines with parcels. If you interact with them you will see a list of potential tasks and their details. The amount you receive depends on distance and time constraints.
If the character has the right skill, then you can get funds by hacking objects. While exploring, you may come across a number of objects, such as ATMs, which you can be hacked. For each of them you will receive additional money. Still, less than when completing story missions. Such places are marked on the map with a currency symbol. Often such places are located in the vicinity of restricted zones.
How to spend money?
Money actually has only one use - buying new clothes. With their help, you can change the appearance of your team. The T-shirt icon on the minimap represents a clothing store.
When you go there, you will be able to choose which part of the outfit you want to buy. You must also remember that there are several different store chains in the city. Each of them offers different style of clothes.