until germany's invasion of poland the democratic nations which had been victorious in world war I had observed all these separate aggressions and done little. the league of nations had all but collapsed in the wake of italy's invasion of ethipia. britain and france had acquiesced in Germany's earlier moves.

i don't understand what that paragraph means. can someone please explain/paraphrase

Let's take it sentence by sentence with appropriate capitalization and punctuation.

Until Germany's invasion of Poland, the democratic nations which had been victorious in World War I had observed all these separate aggressions and done little.

Paraphrase: Before Germany invaded Poland, democratic nations had ignored Germany's aggression.

The League of Nations had all but collapsed in the wake of Italy's invasion of Ethiopia.

Paraphrase: The League of Nations did nothing and was useless after Italy invaded Ethiopia.

Britain and France had acquiesced in Germany's earlier moves.

Paraphrase: Germany and France did nothing while Germany invaded other countries.

In simpler terms, the paragraph is saying that before Germany invaded Poland, the democratic nations that had won World War I had witnessed several acts of aggression by other countries but didn't take much action in response. The League of Nations, an international organization created to promote peace and resolve conflicts, was almost completely ineffective after Italy invaded Ethiopia. Britain and France had also allowed Germany to make certain aggressive moves without much opposition.