expression
in brief; to put it succinctly
A set phrase used to introduce a concise summary or conclusion, often after a longer explanation.
手短に言うと、計画は中止になりました。
In brief, the plan has been cancelled.
手短に言うと、彼の提案は受け入れられなかった。
To put it succinctly, his proposal was not accepted.
Also means 'in short', but つまり is more casual and can be used in more contexts. 手短に言うと is more explicit about summarizing.
A fixed expression composed of 手短に (briefly) and 言うと (if one says). The exact historical derivation is uncertain, but it is a natural collocation in modern Japanese.