Wallonia  is the French-speaking southern part of Belgium. It is wedged between Flanders in the North and France in the South-West, while Luxembourg and Germany share its Eastern border. This region has an immense historical and cultural wealth which is made visible through its buildings, its works of art and its festivals. Every turn of a corner will bring you something new.
As you can see, most of the provinces share their name with the main city (or the nearby country), which makes is a bit complicated. But remember that Flanders has a region called Flemish Ardennes, and the Netherlands has North-Brabant, all for historical reasons.
Nowadays, Wallonia is one of the three federal regions of Belgium (the other two being Flanders and Brussels). This means that it has its own government, a parliament and separate laws. The capital of Wallonia is Namur, near its geographic center, while its largest agglomeration is Liège.
Wallonia occupies the southern half of Belgium. The northern part of the region, around the Sambre and Meuse rivers is heavily urbanised, and this is where most of the population and economical activity concentrate. The southern part of Wallonia is occupied by the Ardennes hills and is way less densely populated than the rest of Belgium. The Ardennes are heavily forested, with a preserved nature. It is thus a good place for hiking, and other nature-related activities.
Wallonia used to have a very good economy, mostly based on charcoal-industry. After the World Wars the industry didn't renew itself fast enough. Because of that the economy is now lagging far behind Flanders. Wallonia is now trying to switch to services rather than heavy industry by, for example, developing logistics around its two main airports.
The official languages of Wallonia are, depending on where you are, French or German. French is spoken in the biggest part of the region (253 out of the 262 municipalities). German is the official language in the remaining 9, situated along the border with Germany. It is very hard to find a German speaker elsewhere in Wallonia outside this region.
Belgian French only differs in minor vocabulary points (called 'belgicisms') from the French spoken in France. Thus, if you learned standard French, you won't have any problems to understand the Walloons.
Wallonia used to have its own language, Walloon. It is closely related to French, though it is not a dialect of it, but a distinct romance language. When Belgium was created, French replaced Walloon more and more. Walloon is now still spoken by the elder generation, but the younger generation rarely knows more than some words of it.
Foreign languages are not as widely spoken in Wallonia as in Flanders though the situation is improving. Dutch is learnt in schools by everyone but for some reasons, like the political conflict with Flanders and above all, the lack of practice (most people in Wallonia rarely go to Flanders), only around 20% of the Walloons are fluent in it. It is much easier to find young people who can speak English, and most people under 30 will be able to help you in English, though sometimes with difficulties. Be aware though it can be hard to have a conversation in English with someone who is 40+. Surprisingly, Spanish is the third most spoken foreign language. Moreover, Liège, Mons and Charleroi have a big italian community. Italian is thus spoken by a certain number of people in these cities.
Anyway, adressing the people in a foreign language is generally not regarded disrespectful, so do not hesitate to do so.
In the biggest tourist locations you will generally get information in English, French and Dutch, but outside it can be hard to have information in an other language than French.