If you throw an object horizontally at a speed v and neglecting air resistance, its horizontal velocity will remain constant throughout its motion. This means that after t seconds, the horizontal velocity of the object will still be v.
However, since the object is subject to the acceleration due to gravity, its vertical velocity will change over time. In the absence of air resistance, the vertical velocity will increase by 9.8 meters per second (acceleration due to gravity) every second. This means that after t seconds, the object's vertical velocity will be approximately 9.8t meters per second downward.
To summarize, the object will have a constant horizontal velocity of v and a vertical velocity of approximately 9.8t meters per second downward after t seconds.