The number of Swedish dialects varies depending on the classification that one uses. The two main dialects are the Svea and Go:ta dialects. (I am using the colon to denote an umlaut) I like to distinguish eight Swedish dialects. They are the dialects of Ska'ne (a' is an "a" with a ring over it), Gotland, Go:taland, Svealand, Dalarna, Va:rmland, Norrland and Finland.
The dialect of Ska'ne is one of the most distinct. It has a uvular trill and a number of diphthongs instead of monophthongs. It lacks the pitch accent present in most Swedish dialects.
Gotland has a dialect which is so different that it is often difficult for other Swedish speakers to understand. It is known for its relatively low intonation and use of diphthongs which do not occur in standard Swedish.
Go:taland, a region which includes Gothenburg, has a strongly trilled "r" and relatively long vowels. The intonation is also distinct.
Svealand, a region which includes Stockholm, has an "r" that is often very softly trilled or pronounced as a fricative or approximant. The intonation is high in comparison to that of most Swedish dialects.
Dalarna has a famous dialect. The "r" tends to be softly trilled, the rhythm is relatively regular and vowels are relatively long.
Va:rmland has a dialect that shares many similarities with the Norwegian spoken in Eastern Norway. The alveopalatal fricative is used instead of the palato-velar fricative of other dialects, the lateral tends to be velarized and the intonation is relatively high.
Norrland is knows for its strongly trilled r, the alveopalatal fricative instead of the palato-velar fricative in many speakers, the deletion of word-final schwa, sentence stress and low intonation.
Finland has a Swedish dialect which uses a strongly trilled r, unaspirated voiceless plosives, a voiceless alveopalatal affricate instead of an alveopalatal fricative, and a single low back vowel instead of a low back vowel and a low front vowel.
Swedish has many dialects, but the eight which I have described here are among the best known. Many Swedes and Swedish-speaking Finns speak dialects that make it possible to determine where they are from.