Quick answer
ojalá
Natural: I hope so / hopefully
Literal: “may God will it”
How it is used
¡Ojalá!I hope so!
Ojalá venga mañana.I hope he comes tomorrow.
Ojalá que tengas suerte.I hope you have luck.
Ojalá pudiera ir.I wish I could go.
Where it is said
It is used across the whole Spanish-speaking world, and the optional <b>que</b> after it is more common in Latin America.
A mini dialogue
— Dicen que mañana hace sol.— They say it will be sunny tomorrow.
— ¡Ojalá!— I hope so!
Watch out
ojalá
It always takes the subjunctive, so ojalá viene is wrong; say ojalá venga.
Check yourself
Which sentence is correct?