Hey, does anyone know what a "huelga general" is?

On the day we took the train from Paris to St. Jean, I noticed posters here and there about a “huelga general” on September 29th. I asked my resident Spanish translator - Kathie, that is - what a huelga is. She didn’t know, nor did my virtually worthless vest pocket Spanish dictionary. From the looks of the posters, I had a sneaking suspicion that it meant strike. Interesting, I thought. It never occurred to me that a strike might affect us in any way…