Blocking, in theatre terms, is when the director tells the actors where they enter, stand, sit, cross, etc. But what do you do during your scenes? Should you be standing in those positions the whole time? The answer is no.
Actors need to develop a sense of awareness of the stage and balance with the other people on the stage. Everyone standing on stage in a line is boring. So think about creating different levels--some actors sitting, others standing, perhaps 2 actors in physical contact, and feel free to use the space on stage while you're speaking.
One common blocking element is called "cross" and "counter-cross". This is when one actor comes close to another actor and then that person then walks to a new position when they speak. This shows clearly to the audience the characters' feelings towards each other and can create dramatic tension in the scene.
When acting, you are driven by the thoughts and motivations of the character, but also be aware that an audience wants to see a dynamic scene, so don't spend too long standing in the same position on stage. Use the stage and show the audience through your body language what your character is feeling.