Generally in terms of a noun, you'd be looking at a significante (which often is paired with significado, or the signified)

It sounds a bit odd in the structure of the sentence you have, though. I would rewrite it as such:

A y B son los significantes de tal concepto.

If you want to retain the structure (and you're not doing a signifier/signified-type relationship), you could say something like

A y B ^significan/_representan tal concepto.
A y B ^simbolizan/_designan tal concepto.
A y B son un símbolo para tal concepto.

Generally in terms of a noun, you'd be looking at a significante (which often is paired with significado, or the signified)

It sounds a bit odd in the structure of the sentence you have, though. I would rewrite it as such:

A y B son los significantes de tal concepto.

If you want to retain the structure (and you're not doing a signifier/signified-type relationship), you could say something like

A y B ^significan/_representan tal concepto.
A y B ^simbolizan/_designan tal concepto.
A y B ^encarnan/_personifican tal concepto. _{(more commonly when A/B are animate)}
A y B son un símbolo para tal concepto.

Generally in terms of a noun, you'd be looking at a significante (which often is paired with significado, or the signified)

It sounds a bit odd in the structure of the sentence you have, though. I would rewrite it as such:

A y B son los significantes de tal concepto.

If you want to retain the structure (and you're not doing a signifier/signified-type relationship), you could say something like

A y B ^significan/_representan tal concepto.
A y B son un símbolo para tal concepto.

Generally in terms of a noun, you'd be looking at a significante (which often is paired with significado, or the signified)

It sounds a bit odd in the structure of the sentence you have, though. I would rewrite it as such:

A y B son los significantes de tal concepto.

If you want to retain the structure (and you're not doing a signifier/signified-type relationship), you could say something like

A y B ^significan/_representan tal concepto.
A y B ^simbolizan/_designan tal concepto.
A y B son un símbolo para tal concepto.