'I can speak'
Should I say 'hanasemasu' or 'hanashite dekimasu' or 'Eigo ga/Nihongo ga/ Furansugo dekimasu? Or are all these right? But watashi wa ninhongo ga hanasu/wakaru koto ga dekimasu/masen would be correct (if rather laborious), yes?

Question

'I can speak'
Should I say  'hanasemasu' or 'hanashite dekimasu' or 'Eigo ga/Nihongo ga/ Furansugo dekimasu? Or are all these right? But watashi wa ninhongo ga hanasu/wakaru koto ga dekimasu/masen would be correct (if rather laborious), yes?

Answer

話せます。（hanasemasu)、～語ができます。（~go ga dekimasu) are reight.
But "hanashite dekimasu" is improper expression in this situation.