They're based on creatures and household appliances, similar to the "Junk Robots" and the "Morphtronics". Also, similar to the "Morphtronics" (with change in effect(s) based on their battle position), Link Appliancer monster's effects depend on whether they are co-linked or not.
In Japanese, the archetype is named after "機械" (Kikai), or "appliance", but the last kanji has been replaced with "塊", which can mean "mass", "group", or "personification". So, the direct translation of the name can mean "Mecha Mass". In the Japanese version of the anime and OCG, Appliancers also have an adjective describing their function (for example, Fanning Appliance Propelion) which is omitted in the Crunchyroll official subs. Individually their names are combinations or portmanteaus of their appliance and creature themes.
"Appliancer" Main Deck monsters tend to be of low level and low ATK/DEF values, but have abilities that allow swarming. "Appliancer" Link Monsters all have effects that change whether they are co-linked or not. Given the vast majority of "Appliancer" Link Monsters are of low Link Rating, it is fundamentally easy to fill the field with many of them which by proxy reduces the complexity of co-linking many of them at once.
Despite the fact "Appliancer" Link Monsters have low ATK value as to be expected from their low rating, their powerful co-linked effects compensate for this weakness.