1.46 understand that a metal can be described as a giant structuree of positive ions surrounded by a sea of delocalised electrons

In a metal, the atoms are ionically bonded in a giant 3-D structure. The outer shell electrons become detached (making positive ions, cations). The cations are 'floating' in a sea of delocalised electrons. The metal structure stays together because the cations (+) are attracted to the electrons (-). This is known as a metallic bond.

1.47 explain the electrical conductivity and malleability of a metal in terms of its structure and bonding.

Metals are a giant 3-D structure of positive ions surrounded by delocalized electrons.

Electrons carry electricity. Metals are good conductors of electricity as they have lots of delocalized ('free') electrons that are free to move when a voltage is applied, carrying a charge through the metal.
Metals are structured with layers of positive ions on top of eachother. These ions can easily slide over one another as (in pure metals) they will all be the same size. As they can easily slide, this means they are malleable and ductile.

NOTE: The metallic bonds (force between cations and delocalized electrons) are not broken when metals are moulded as the electrons 'travel' with the cations.