What is SpectralEmbedding in sklearn?

Question

I am using Affinity Propogation to cluster my similarity matrixsims. My code is as follows. According to an answer of my previous question I am using SpectralEmbedding to plot my data points of the similarity matrix sims.

import sklearn.cluster
from sklearn.manifold import SpectralEmbedding
import numpy as np
import matplotlib.pyplot as plt
from itertools import cycle

sims =  np.array([[0, 17, 10, 32, 32], [18, 0, 6, 20, 15], [10, 8, 0, 20, 21], [30, 16, 20, 0, 17], [30, 15, 21, 17, 0]])

affprop = sklearn.cluster.AffinityPropagation(affinity="precomputed", damping=0.5)
affprop.fit(sims)

cluster_centers_indices = affprop.cluster_centers_indices_
print(cluster_centers_indices)
labels = affprop.labels_
n_clusters_ = len(cluster_centers_indices)
print(n_clusters_)

se = SpectralEmbedding(n_components=2, affinity='precomputed')
X = se.fit_transform(sims)

plt.close('all')
plt.figure(1)
plt.clf()

colors = cycle('bgrcmykbgrcmykbgrcmykbgrcmyk')
for k, col in zip(range(n_clusters_), colors):
    class_members = labels == k
    cluster_center = X[cluster_centers_indices[k]]
    plt.plot(X[class_members, 0], X[class_members, 1], col + '.')
    plt.plot(cluster_center[0], cluster_center[1], 'o', markerfacecolor=col,
             markeredgecolor='k', markersize=14)
    for x in X[class_members]:
        plt.plot([cluster_center[0], x[0]], [cluster_center[1], x[1]], col)

plt.title('Estimated number of clusters: %d' % n_clusters_)
plt.show()       

However, I do not understand what exactly happens with SpectralEmbedding. Please let me know what it does? And is it correct to use SpectralEmbedding to plot similarity values?