In the context of Nova Scotian research, the term Foreign Protestants refers to a group of immigrants who were recruited by the British to help settle Nova Scotia starting in 1750. The British, led by Lord Cornwallis, wanted to reduce the high percentage of French Catholic Acadians who remained in the area after Nova Scotia was ceded to the British in 1713 by the Treaty of Utrecht. British colonists were choosing other colonies over Nova Scotia and so the British recruited "foreign" Protestants, mostly Germans, but also some Swiss, Dutch, and French.
The recruiting effort was successful, mostly because the British government promised free passage, land, and rations to the immigrants. The German, Swiss, and Dutch influence is evident in Nova Scotia today, especially along the South Shore.
Even after importing a large number of immigrants, Nova Scotia was still mostly Acadian. This was untenable to the British, and led to the eviction of the Acadians between 1755 and 1753.
For more info, read: http://en.wikipedia.org/wiki/Foreign_Protestants